Pushbutton tuning keyboards are known for preselecting electromagnetic signals, wherein a frame carries a tuning system which is operable either by means of a conventional rotary manual knob tuning mechanism provided with a disengageable clutch means or by means of a number of pushbutton keys, each having stored thereon a predetermined position to be imparted to the tuning system. One such tuning system comprises a tuning slider that is longitudinally slideably reciprocable with respect to the frame and whose position determines the selection of electromagnetic radio signals. The tuning slider is provided with a number of slots and a number of elbow levers are pivoted on the frame and each elbow lever has one end coacting with one slot of the tuning slider. An adjustable means selectively engaging the other end of each of said elbow levers is provided on each of said pushbutton keys, the keys being slideably guided on the frame at right angles to the movement of the tuning slider, the keys also being reciprocably moveable between an extracted rest position and a retracted operative position in which operative position the adjustable means imparts a preselected rotation to the corresponding elbow lever and thereby a preselected longitudinal movement to said tuning slider. Such a pushbutton keyboard tuning system is described in a copending U.S. patent application, Ser. No. 731,331 assigned to the same assignee as the present invention.